TST: Unignore FITSFixedWarning

[pllim]

Address one warning from #927

[pllim]

Could it be this easy? No changes to test code?!

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 70.03%. Comparing base (0ac49cf) to head (72629af). Report is 143 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1040   +/-   ##
=======================================
  Coverage   70.03%   70.03%           
=======================================
  Files          64       64           
  Lines        4345     4345           
=======================================
  Hits         3043     3043           
  Misses       1302     1302           

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[pllim]

17 failed all from remote data, I see...